ACS makes lowering springs for the GC xdrive:
http://shop.ac-schnitzer.co.uk/suspe...rom-5051-p.asp
Confirmed this on ACSs website price list.
My biggest concern about the HRs is that they seem to list the same part number for several cars (at least the ones I've checked), including the GC xdrive. When you consider the weight differences between all of these cars, I have doubts that "one spring" is able to do it all. I'll be asking my dealer about the ACS and if they would have any extra grief if they were installed.